them square, as in this way you will prevent them from ingrowing under
the pressure of your shoes.

There is one thing that you should be very sure of before you get into
bed, and that is that your teeth are as clean as it is possible for
you to make them. If you attended to this also directly after supper,
so much the better; for just as it is important to clean the dishes
and knives and forks that you have been using, so it is important to
thoroughly clean the ivory knives and forks that grow in your mouth.
Talk about being "born with a silver spoon in your mouth"! You were
born with something much prettier and far more valuable.

Even though your teeth make a firm and even line in front and on their
cutting edges, yet there are many little gaps and spaces between their
roots, where bits of food can stick. If these scraps of food are not
thoroughly and carefully removed after each meal, the warmth and
moisture in the mouth makes them begin to decay. The acids from this
decay will be likely not only to upset your stomach and digestion, but
to act upon the glassy coating of your teeth. After a little while,
spots will begin to form on the surface of your teeth; they will lose
their bright, shiny, pearly look; the acids will eat further into the
teeth, and very soon there will be holes, or _cavities_.

Though your teeth are very hard and glassy looking on the surface,
they are much softer and chalkier inside; this glassy coating covers
only the _crown_, or free part, of the tooth, which you can see. It
leaves the softer inside part of the tooth bare just at the edge of
the gums, and particularly between the roots of the teeth, where
little scraps of food lodge and decay. When the acids that are formed
by the decaying food have eaten away a good deal of the inside of the